MEDICAL TERMINOLOGY

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MEDICAL TERMINOLOGY

• THE LYMPHATIC AND IMMUNE SYSTEMS

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FUNCTIONS OF THE IMMUNE SYSTEM

• Protect the entire body from a variety of harmful
  substances
• Our immune system is not contained within one
  body organ, but it is part of the lymphatic,
  cardiovascular, and integumentary systems

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Functions of the Lymphatic System

• Return excess lymph fluid to the blood
• Absorb fats and fat-soluble vitamins from the
  digestive system and transport them to the cells
• Function as part of the immune system

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The Lymphatic System

• The Lymphatic System is composed of several
  structures, namely
• Lymph
• Lymph Vessels
• Lymph Capillaries
• Lymph Nodes
• Lets examine each of these structures

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LYMPH

• Lymph is a specialized fluid formed in the tissue
  spaces that is transported by way of specialized
  Lymphatic vessels.
• Lymph fluid also called interstitial fluid is
  composed of water, lymphocytes, digested
  nutrients, hormones, salts, carbon dioxide,
  oxygen, and urea. The fluid flows in spaces
  between the cells and tissues so it can carry
  substances from the tissue back to the blood
  stream.

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LYMPH FLUID

• How is lymph fluid formed?
• Blood plasma filters out of the capillaries into
  the microscopic spaces between tissue cells
  because of the pressure generated by the pumping
  action of the heart. Part of this lymph fluid or
  interstitial fluid goes back into the blood and
  part of the fluid enters the lymphatic system
  before it returns to the blood

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LYMPH FLUID

• Lymph fluid always flows toward the thoracic
  cavity where the right lymphatic duct and the
  thoracic duct empty lymph into the veins. Lymph
  from about 3/4 of the body eventually drains into
  the thoracic duct

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Lymph Vessels Capillaries

• Lymph Vessels have valves and prevent the
  backward flow of lymph fluid
• Lacteals are specialized lymph vessels located in
  the small intestines where fats and fat-soluble
  vitamins are absorbed into the bloodstream

• Lymph Capillaries are small tubes that carry
  lymph fluid from the tissue spaces to the lymph
  vessels

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Lymph Nodes

• Lymph nodes are small round structures, some as
  small as pin heads others as long as lima beans.
  Lymph nodes are located in lymph vessels. What
  do they do?
• Lymph nodes fight disease producing antibodies
  and purify lymph by removing harmful substances.
  They house B cells and T cells of the immune
  system
• .

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Why is Knowing About Lymph Nodes Important

• Sometimes tumors may metastasize from the lymph
  nodes and spread to other parts of the body.
• Lymph nodes perform biological filtration of
  bacteria and other abnormal cells which prevents
  local infections from spreading

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Lymph Node Sites

• Cervical lymph nodes located in the neck
• Inguinal lymph nodes located in the groin area
• Axillary lymph nodes located under the arms
• Appendix Peyers patches lymph nodes located in
  the intestine

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Other Parts of the Lymphatic System

• Tonsils
• Adenoids
• Spleen
• Thymus

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Tonsils Adenoids

• The tonsils are a mass of lymphatic tissue
  located in the upper portion of the throat
• The palatine tonsils are located in the
  oropharynx
• The lingual tonsils are located on the back of
  the tongue
• The tonsils help protect us against bacteria that
  may invade tissues in the area around the
  openings between the nasal and oral cavities

• The adenoids are located in the nose and may also
  be called

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The Spleen

• The spleen is a mass of lymphatic tissue located
  in the left quadrant of the abdomen.
• The spleen produces lymphocytes and monocytes
• The spleen filters microganisms and other foreign
  matter from the blood.
• The spleen also stores red blood cells to
  maintain the appropriate balance between cells
  and plasma
• The spleen is hemolytic which means it removes
  and destroys worn our blood cells
• The spleen also produces bilirubin which is the
  yellow/orange pigment in bile

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The Thymus

• The thymus is made of lymphatic tissue and is
  located in the anterior of the thorax superior.
• The thymus produces lymphocytes
• The thymus is largest at puberty and even them
  weighs only about 28 grams

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THE IMMUNE SYSTEM

• The immune system works to protect the entire
  body from many harmful substances. The immune
  system isnt contained in any organ or vessel and
  is made up of billions of cells and trillions of
  molecules
• The skin is the bodies first line of defense
  against an invading organism
• The respiratory system is the bodies next line of
  defense against an invading organism
• The digestive system also has a protective
  function destroying bacteria and other invaders
  that are swallowed or consumed with food

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Immune Reaction

• Antigenany substance the body regards as foreign
  such as a bacteria, fungus, virus, toxin, etc.
• Antibodyalso referred to as an immunoglobulin is
  produced by B lymphocytes in response to the
  presence of an antigen. Antibodies neutralize or
  destroy antigens in several ways. They can
  initiate destruction of the antigen by
• Activating the complement system
• Neutralizing toxins released by bacteria
• Coat the antigen or forming a complex to
  stimulate phagocytosis
• Promote antigen clumping
• Prevent the antigen from adhering to host cells

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IMMUNE SYSTEM CELLS

• The primary cells of the immune system include
• Phagocytes
• Lymphocytes
• Immunoglobulins
• Complement Proteins
• Lets examine each of these cells

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Phagocytes

• Phagocytes are cells derived from the bone marrow
  that carry on phagocytosis or ingestion and
  digestion of foreign cells. There are four types
  of phagocytic cells
• Neutrophils
• Monocytes
• Macrophages
• Histocytes

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Lymphocytes

• Lymphocytes as you know are a major class of
  white blood cells that attack specific
  microorganisms. Lymphocytes are agrandular
  leukocytes
• There are two major types of lymphocytes
• T-lymphocytes
• B-lymphocytes

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T-Lymphocytes

• T-lymphocytes or T-cells circulate lymphocytes
  produced in bone marrow. They mature in the
  thymus and they aid in cellular immune responses
  and destruction of virus cells and cancer cells.
  There are several byproducts of T-cells
• Helper T-cells--stimulate the production of
  antibodies by B-cells
• Supressor T-cells--suppress B-cell activity
• Lymphokines--produced by T-cells and they attract
  macrophages to an area of infection and then
  attack
• Interferon--produced by T-cells and are a protein
  substance released by cells when invaded by a
  virus. They also form an antiviral protein to
  inhibit viral muliplications

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B-lymphocytes Immunoglobulins

• Immunoglobulins are antibodies made by plasma.
  An immunoglobulin is any of five distinct
  antibodies present in the serum and external
  secretions of the body.
• Lets examine immunoglobulins more closely

• B-lymphocytes are produced in bone marrow and is
  designed to make a specific antibody against a
  specific antigen

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Types of Immunoglobulins

• Immunoglobulin A--the major antibody in the
  mucous membrane lining of the intestines,
  bronchi, saliva, and tears. Protects epithelial
  surfaces
• Immunoglobulin D--found in serum tissue, possibly
  influences B lymphocyte differentiation
• Immunoglobulin E--found in the lungs, skin, and
  cells of mucous membranes. Provides the defense
  against environmental antigens, becomes active in
  allergic reactions and some parasitic infections
• Immunoglobulin G--is a specialized protein
  synthesized in response to the invasion by
  bacteria, fungi, and viruses (germs). Crosses
  placenta to provide passive immunity for the
  newborn. Activates complement system.
• Immunoglobulin M--produced when challenged by
  antibodies and circulates in fluids of the body.
  Activates complement.

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Complement Proteins

• Complement Proteins are 14 complex enzymatic
  proteins occurring in serum. When they are
  activated they form a highly specialized
  antigen-antibody complex that targets foreign
  cells for destruction or lysis.
• Lysis is the penetrating of a cell wall allowing
  fluid to fill the cell and cause the cell to
  rupture

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Pathology of the Immune System

• Hypersensitivity or an Allergy--is an
  inappropriate or excessive response of the immune
  system to a particular allergen that in most
  people does not cause any problem.
• Allergen is a substance capable of inducing an
  allergy. One in six Americans has a genetic
  predisposition to exhibiting an allergy of some
  kind

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Bodys Immune Response

• Foreign substance enters of body
• Activation of the body as the defense system
  produces more white blood cells that are designed
  to seek and destroy the invader, especially the
  macrophases that eat and engulf the foreign
  substance and lymphocytes, B cells, and T cells
  constitutes the second phase. T cells of the
  helper type identify the foreign substance and
  rsuh to the spleen and lymph nodes where they
  stimulate the production of other cells to aid in
  the fight of the foreign substance. B cells
  reside in the spleen or lymph nodes and produce
  antibodies for specific antigens if needed.

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Bodys Immune Response

• During the attack phase, the above defenders of
  the body produce antibodies and or seek ot to
  kill or remove the foreign invader. This is done
  by phagocytosis where the macrophages squeeze out
  between the cells in the capilaries and crawl
  into the tissue to the site of the infections.
  Here they are surrounded and eat the foreign
  substance that caused the infection. Other white
  blood cells respond to infection where they
  surround and immobilize the invaders.
• In the last phase, the number of defenders
  returns to normal, following victory over the
  foreign invader.

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Pathology of the Immune System

• Autoimmunity is an inappropriate and excessive
  response to self-antigens or simply the bodys
  defenses attack its own tissues.
• A common disease is systemic lupus erythematosus
  or lupus which is a chronic inflammatory disease
  that affects many tissues of the body
• Isoimmunity is excessive reaction of the immune
  system to antigens from a different individual of
  the same species. An example is the body and
  transplants

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Immunity

• Immunity is simply the bodies resistance to a
  disease. There are two kinds of immunity
• Active immunity obtained by the development of
  antibodies because you have had an infection or
  you are vaccinated or inoculated against a
  disease
• Passive immunity passed from the mother to a
  child or through the injection of antibodies

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Immunodeficiency

• Immunodeficiency is the failure of the immune
  system mechanism in defending against pathogens.
  The immune system failure usually results from
  disruption of lymphocyte function. The cheif
  characteristic of immune deficiency is the
  development of unusual or recurring severe
  infectins or cancer. Although immune deficiency
  by itself does not cause death, the resulting
  infections or cancer can.

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Immunodeficiency

• Now that you know what immunodeficiency is, you
  need to know that there are two broad categories
  of immune deficiencies
• Congenital immune deficiency
• Acquired immune deficiency which is a disease
  caused by human immunodeficiency virus that
  destroys part of the bodys immune system and
  leaves victims unable to defend themselves
  against opportunistic infections and cancers

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